OSI Model - Reference graphic / What do you guys think? Anything to edit/remove/add?
OSI Model - Reference graphic / What do you guys think? Anything to edit/remove/add?
In case anyone's a CS student in need of a pneumonic to remember the OSI layers, a professor gave me this one and it's stuck with me for years:
(From top to bottom) All People Seem To Need Data Processing.
All people say they never download porn
What is the OSI Model? OSI Model Layers Explained
Please do Not Touch Steve's Pet Alligator
For this exercise, let’s use the mnemonic “Please Do Not Touch Steve’s Pet Alligator.”
Layer 1: Physical = Please
Layer 2: Data Link = Do
Layer 3: Network = Not
Layer 4: Transport = Touch
Layer 5: Session = Steve’s
Layer 6: Presentation = Pet
Layer 7: Application = Alligator
To easily remember the OSI 7-layer model, you can use the mnemonic: "Please Do Not Throw Sausage Pizza Away". Each word corresponds to a layer in the OSI model from the lowest (Physical) to the highest (Application):
- Please (Physical)
- Do (Data Link)
- Not (Network)
- Throw (Transport)
- Sausage (Session)
- Pizza (Presentation)
- Away (Application)
https://en.wikipedia.org/wiki/OSI_model
The Open Systems Interconnection model (OSI model) is a conceptual model that 'provides a common basis for the coordination of [ISO] standards development for the purpose of systems interconnection'.[2] In the OSI reference model, the communications between a computing system are split into
seven different abstraction layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.[3]
The Internet protocol suite has a separate model, the layers of which are mentioned in RFC 1122 and RFC 1123.
That model combines the physical and data link layers of the OSI model into a single link layer,
and has a single application layer for all protocols above the transport layer, as opposed to the separate application, presentation and session layers of the OSI model.
Physical, Data Link, Network, Transport, Session, Presentation, and Application. 这样子的话,变成了四层。
The OSI (Open Systems Interconnection) model is a conceptual framework used to understand and standardize the functions of a telecommunication or computing system without regard to its underlying internal structure and technology. It is organized into seven layers, each of which serves a specific function and interacts with the layers directly above and below it. Here is an overview of each layer:
-
Physical Layer (Layer 1):
- Function: Deals with the physical connection between devices and the transmission and reception of raw bit streams over a physical medium (e.g., cables, wireless).
- Key Components: Cables, switches, hubs, physical network interfaces, radio frequencies.
- Examples: Ethernet cables, fiber optics, Bluetooth.
-
Data Link Layer (Layer 2):
- Function: Provides node-to-node data transfer, error detection and correction, and frames the data packets.
- Sub-layers: Logical Link Control (LLC) and Media Access Control (MAC).
- Key Components: Switches, bridges, network interface cards (NICs).
- Examples: Ethernet, Wi-Fi (IEEE 802.11), MAC addresses.
-
Network Layer (Layer 3):
- Function: Manages the routing of data packets between devices across different networks, handles logical addressing and path determination.
- Key Components: Routers, Layer 3 switches.
- Examples: IP (Internet Protocol), ICMP (Internet Control Message Protocol).
-
Transport Layer (Layer 4):
- Function: Ensures reliable data transfer between end-to-end systems, provides error correction, flow control, and data segmentation and reassembly.
- Key Components: Transport protocols, ports.
- Examples: TCP (Transmission Control Protocol), UDP (User Datagram Protocol).
-
Session Layer (Layer 5):
- Function: Manages sessions between applications, controls the dialog between two devices, and establishes, maintains, and terminates connections.
- Key Components: Session management protocols.
- Examples: NetBIOS, RPC (Remote Procedure Call).
-
Presentation Layer (Layer 6):
- Function: Translates data between the application layer and the network, handles data encryption, compression, and translation of data formats.
- Key Components: Data conversion protocols.
- Examples: SSL/TLS (Secure Sockets Layer/Transport Layer Security), JPEG, ASCII, EBCDIC.
-
Application Layer (Layer 7):
- Function: Provides network services directly to end-user applications, facilitating communication between software applications and lower network services.
- Key Components: Application protocols.
- Examples: HTTP (Hypertext Transfer Protocol), FTP (File Transfer Protocol), SMTP (Simple Mail Transfer Protocol), DNS (Domain Name System).
Summary
- Physical Layer: Deals with the physical medium of transmission.
- Data Link Layer: Ensures error-free transmission between adjacent nodes.
- Network Layer: Manages logical addressing and routing.
- Transport Layer: Provides reliable data transfer and error handling.
- Session Layer: Manages sessions and connections.
- Presentation Layer: Translates data formats and handles encryption/compression.
- Application Layer: Provides network services to applications.
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